It is often required for a vehicle to be maneuvered into a position near one or more objects. For example, it is common for a truck or the like to be required to be reversed into a loading/unloading bay. Often, it is very difficult for a driver of the vehicle to determine how far a rear end of the vehicle is positioned from the loading bay, and thus, frequently, the vehicle collides with the loading/unloading bay through an error in judgement by the driver. Such collisions often cause serious damage to the loading/unloading bay and/or to the rear of the vehicle.
In an effort to avoid this problem, it has been proposed to provide the rear of the vehicle with a distance sensor which senses a distance between a rearmost part of the vehicle and the closest object near the rear of the vehicle and to use the distance determined by the distance sensor automatically to reduce the speed of the vehicle to ensure that the vehicle does not collide with the object.
Such a system is disclosed in U.S. Pat. No. 6,604,592. In this prior art system, when the vehicle is placed in reverse mode, sensed distance values from the distance sensor are sent to a controller, and the controller limits the speed of the vehicle to a maximum permissible vehicle speed value which depends on the distance value detected by the distance sensor. If the distance value is greater than a first amount, the maximum permissible vehicle speed is set to a first value; if the distance value is less than the first amount by greater than a second amount, the maximum permissible vehicle speed is set to a second value; and if the distance value is less than the second amount, the vehicle speed is controlled such that the vehicle comes to a stop before contacting the object.
Examples of similar prior art systems are also disclosed in U.S. Pat. No. 3,898,652, U.S. Pat. No. 4,574,908, and GB 2458655.
In all these systems, the distance sensors are active, or signals from the distance sensors are processed and acted on, only when the vehicle is in reverse gear. As a result, there is no automatic application of the vehicle brakes as a result of the proximity to an object at the rear of the vehicle when the reverse gear is not engaged.